How to get Global object location - Python
Thanks @Jaroslav Jerryno Novotny for help: I'm dumb because I forgot to select everything and set origin to center of its surface/volume (every object had pivot in the middle).
But anyway thanks for "objectTrawa.matrix_world.translation" I will use it instead of location
and zfill() function (I didn't even think that this would be so good for my code)

final code

ObjectNameNumber = 1

for i in range(1,649):      
        ObjectName = "Trawa." + (str(ObjectNameNumber).zfill(3))
        objectTrawa = bpy.data.objects[str(ObjectName)]
        objectTrawa.select = True
        print(ObjectName, "and its location is: ",     objectTrawa.matrix_world.translation)
        #bpy.ops.object.select_all(action='DESELECT')
        ObjectNameNumber+=1